Pallets are currently constructed by a fabricating process to have upper and lower platforms and blocks or beams therebetween, enabling a forklift truck to position its forks within or beneath the pallet on at least two sides, preferably four sides. However the production methods are expensive, the costs of the pallets are high and the likelihood of damage is also high, and accordingly it has been proposed heretofore to arrange a pallet to be formed from plastics material, formed for example by a drape moulding process, to have a plurality of cup-like portions which can rest upon the ground but raise a platform area above the ground. Such pallets are however subject to a number of disabilities. Firstly, plastics material is not sufficiently rugged to withstand general usage unless very expensive reinforced resins are used. Secondly, there is usually an area near the centre of the platform of the pallet which is likely to deflect upon a load being imparted. Thirdly, the cost is high if the material thickness and resin type is sufficient to provide even moderate strength.
Because of the high cost of fabricating steel pallets, use is still made mostly of wooden pallets, and the main object of this invention is to provide improvements in pallets, and also in their method of production, whereby steel or other sheet metal may be used.
In the pressing of steel there are two recognised functions, one known as "metal flow" wherein metal can flow from around an area in which a cup-like depression is to be formed, so as to form the cup-like depression and the second is known as a "metal stretch" wherein the metal is actually elongated and attenuated in thickness. It is also known to form a comparatively deep cup-like depression by firstly forming a shallow cup-like depression with predominately a metal flow process and only a small amount of metal stretch, and subsequently reducing diameter but increasing depth again with mostly a metal flow process. This arrangement would be satisfactory for example for forming a plurality of supports near the periphery of a pallet, but is completely unsuitable for forming a central cup-like depression, but a central support is usually required for a pallet. The reason for this is that when the peripheral cup-like depressions are formed, the metal flows from all directions to form those depressions, including from the centre of the pallet platform, but metal flow in a reverse direction is required to form a central depression. It will be appreciated that, in order to ensure a pallet is universally usable, it must accept not only the forks of a forklift truck but also the forks of a hand truck, and consequently a depth of about 95 mm is required.
Because of the abovementioned difficulties it has heretofore been considered not practicable to form a shape similar to what is required to provide not only peripheral supports but also a central support for the platform.